This invention relates generally to string instruments, and more specifically to, an anti-wolf-note resonator assembly for a string instrument and method of assembling the same.
Well constructed, string instruments, such as a cello, may generate a wolf-note when the instrument is played. More specifically, when played, known instruments produce an intended note that vibrate at an intended frequency. However, depending on a strength or amplitude of the intended note, an errant portion of the instrument may vibrate, rattle, flap, or resonate, producing an unintended note at a frequency that is different than that of the intended note. If the instrument produces both the unintended note and the intended note simultaneously, the combined acoustical interference, called a beat, may cause the wolf-note sound to be generated. It is a common practice to refer to both the unintended note and the intended note as the wolf-note, since both may be so close in tone that they sound almost like the same note. However, as is known by those skilled in the art, the wolf-note sounds like a wolf howl and the amplitude modulation is generally uncontrollable and annoying, and may prevent the player of the string instrument from producing a steady clear note. The above explanation, the beating of two notes, is not the only explanation offered in the literature to explain the wolf note. However, for this discussion and for simplicity we will assume that the theory of the beating of two notes describes the wolf-note phenomena.
As a slight digression, we offer, for completeness, a second wolf-note theory. We will call this the “mobile-bridge” theory as opposed to the above “beat-frequency” theory.
In the mobile-bridge theory, the amplitude of the bridge is so great that it periodically dampens the string vibration. For a string to vibrate in a standing wave it has to be firmly fixed at both ends. However in string instruments one end of the string is fixed at the nut near the scroll and the other end is allowed to also vibrate at the bridge. The bridge can vibrate in two modes of oscillation, either in phase with the string or out of phase with the string vibration. If the bridge is out of phase with the string, it will drive the string by reflecting wave energy back into the string. If the bridge is in phase, it will tend to dampen string vibration by moving out of the way and hence absorb wave energy. In practice, the bridge will vibrate back and forth between these two modes. Thus the string will periodically vibrate stronger when out of phase with the bridge, and vibrate weaker when in phase. This vibrating stronger and weaker-in phase and out of phase-is the wolf note sound.
The mobile-bridge theory explains why cellos more often have a wolf note as compared to violins and violas. It is because the cello's bridge is proportionally taller. Thus the top of the cello bridge has greater amplitude of vibration and hence vibrates in and out of phase more easily.
Typically, the wolf note occurs at a frequency where the cello vibrates the strongest, at what is called the main wood mode of oscillation. This is the simplest, greatest amplitude, and lowest mode of vibration for the top of the instrument. To prevent the wolf note we need to reduce this exaggerated vibration.
At least one known method to suppress the wolf-note is to take energy away from the main wood mode of oscillation by attaching a weight to a string of the instrument such that the weight is positioned between the bridge of the instrument and the tailpiece of the instrument. The weight must be tuned to oscillate at the frequency of the main wood vibration. However, as is known, the size and position of the weight on the string may be critical to suppressing the wolf note. For example, as the string ages and/or stretches, the string may require retuning. After retuning, the weight may need repositioning to be effective in suppressing the wolf-note. Moreover, such devices may provide only limited results, and as such the main wood note may still remain uncomfortably loud although the wolf note has been suppressed.
Another known solution in suppressing wolf-notes is to permanently attach a resonant weighted device, a damper, to the string instrument. A musician, through trial and error, determines the most effective or optimum location for such a device. Once the most effective position is identified, the device is inserted into the cavity of the instrument and is permanently coupled to an interior surface of the instrument. Because the devise is permanently coupled to the instrument with an adhesive material, it cannot easily be repositioned, and/or cannot be removed without the assistance of a repair shop.